Jared Sullinger is still very young. Jason Collins is playing with his fifth team in six years. “Darko Milicic” is Serbian for “squandered potential.” Fab Melo is perhaps too raw and too far away to even bring into this conversation yet.

But there are clear and available roles for all with the exception of project Melo, and, combined, they represent a fair leap forward for the Celts from last season. And this is without even getting into holdovers Brandon Bass, Chris Wilcox and, of course, Kevin Garnett.

Sullinger is proving basketball-wise beyond his years, Collins is a solid defender who won’t get lost in the Celtics scheme, and Milicic could finally expand into a true contributor as his role narrows. Or as one former NBA player told us, “Doc may be the guy who can get through to Darko and get that talent out of him. And it helps having KG in his ear, too.”